House Democrats are bracing for defections during Thursday's vote to hold Attorney General Eric Holder in contempt of Congress after the National Rifle Association (NRA) announced they will be including the vote in their "future candidate evaluations."

"It is no secret that the NRA does not admire Attorney General Holder," a letter from the NRA to members of the House of Representatives reads. "For years, we have pointed out his history of anti-second Amendment advocacy and enforcement actions."

In an effort to persuade Democrats from voting for the contempt citation because of their fear of repercussions from the enormously powerful gun lobby, aides say that House Minority Whip Steny Hoyer (D-MD) is actively engaging members of their caucus to encourage them to vote against the measure, something called "whipping" on Capitol Hill.

"I think there are some members that will consider the recommendations of the NRA," Hoyer said to reporters today. "Whether they think those recommendations are founded or not, I don't know at this point."

The number of Democratic defections could reach 31, according to House Oversight Committee Chairman Darrell Issa (R-CA), whose committee voted last Wednesday to move the contempt citation to a full House vote.

Issa cites a letter sent from 31 Democrats to the Obama administration last year asking for them to be forthcoming with details of the Fast and Furious gun-walking operation as a template for possible Democratic "yes" votes.

While 31 Democrats voting for the contempt citation on Thursday may be overly optimistic, the sway of the NRA during an election year is a legitimate concern for Democrats. Democrats running in swing districts need the support of organizations like the NRA (or at least not their opposition) to stop more conservative opponents from taking them down in November.

But the NRA has made it crystal clear that it supports finding Holder in contempt of Congress, and they think members of Congress should as well.

"The reason we support the contempt resolution is the same reason we first called for Attorney General Holder's resignation more than a year ago: the Department's obstruction of congressional oversight of a program that cost lives in support of an anti-gun agenda," the NRA's letter reads. "This is an issue of the utmost seriousness and the NRA will consider this vote in our future candidate evaluations."